Copending application Ser. No. 562,317 filed Mar. 26, 1975, discloses an input/output data processing system which provides communication and control functions in a larger data processing system. Particularly, the application is directed to the processor portion of the I/O system which, inter alia, develops addresses to data which may be stored in memory units utilizing known paging techniques. Paging allows the storage of data in units or pages which may be stored in local memory, remote memory, or in bulk storage.
Copending application Ser. No. 562,330 filed Mar. 26, 1975, discloses a method of generating addresses to paged memory, particularly applicable to the I/O system and processor of application Ser. No. 562,317, utilizing a page table word scratchpad and page table words which define memory locations for respective pages of data.
In the described modular I/O system, a system interface unit (SIU) interconnects various units including the I/O processor, a plurality of local memories, and a plurality of remote memories. In developing addresses to these various memory units, steering to specific units (or initiating a fault procedure for data not in memory) is required. Heretofore, processors have been provided with special memory configuration logic to facilitate fetches of data in a system employing plural memories. Not only has additional hardware been required but additional time is required in fetching data other than the time necessary for memory address development.